116 



and Asilid flies were found preying on representatives of the following 

 genera : — Dorcaloemus 2, Chrysops 1, Silvius 22, Haematopota 37, 

 Tabanus 13, while examples of a fossorial wasp, Bembex md6M, Handl., 

 were captured in the act of carrying off females of T. taeniola and 

 Haematopota mactans, which were feeding on cattle. 



The investigation of Tabanid larvae, which was the chief object of 

 the author's visit, was at first delayed by the difficulty of locating 

 them, but ultimately numbers were obtained from the sand and mud 

 on the edges of rivers, streams and swamps. It appears probable, 

 from the observations made, that the bulk of Nyasaland Tabanidae 

 have only one brood a year ; certain species of Chrysops and Haema- 

 topota may possibly be double-brooded, but this depends greatly on 

 larval food supply and local conditions. The question of distinct broods 

 is complicated by the fact that larvae from the same batch of eggs 

 vary greatly in their rate of growth and a proportion of the imagines 

 emerge at very irregular intervals. Details are given of the methods 

 found best for rearing and feeding the larvae, which, in their resting 

 stage, may remain weeks or even months several inches below the 

 surface of the mud ; this habit would appear to be an adaptation to 

 cUmatic conditions in Nyasaland, the very long and well-marked dry 

 season involving risk from the drying up of the mud at less depths. 

 Adult Tabanids are exceedingly difficult to keep ahve in captivity, 

 but large cages with soft elastic walls of mosquito netting were found 

 fairly satisfactory, otherwise the insects damage themselves against 

 the cage. It is difficult to induce them to suck blood in captivity, 

 though they will feed readily on honey and water. Breeding can 

 probably only be successfully carried out in cages large enough to 

 contain a good -sized mammal. The females are not easily disturbed 

 when ovipositing. The cement covering of the egg-masses is very 

 insoluble, and some eggs hatched out after the mass had been immersed 

 in 70 per cent, alcohol for two days. The young larvae grow slowly 

 at first and are very active in water ; the older ones are more or less 

 nocturnal in their habits, and those of most species are frequently 

 cannibalistic. 



Fifty-six species are recorded, with notes on the habits of both larvae 

 and adults in several cases. The text-figures include a large number 

 of drawings of the terminal asters of the pupae which are useful in 

 distinguishing them. The following species are described as new : — 

 Silvius apiformis, a remarkable bee-like species confined to forested 

 rivers ; Silvius nionticola, taken at 6,500 feet on the Mlanje Plateau ; 

 Chrysops bimaculosa ; C. woodi and C. austeni, two brilliantly coloured 

 species which seem to form a distinct group among the African 

 representatives of this genus. 



Some of the early stages of the following species are described and 

 figured -.—Chrysops longicornis, Macq., C. magnifica, var. inornata, 

 Aust., C. welimani, Aust., C. bimaculosa, sp. n. ; Haematopota in- 

 satiabilis, Aust., H. crudelis, Aust., H. decora, Walk. ; Tabanus 

 macidatissimus, Macq., T. corax, Lw., T. biguttatus, Wied., T. taeniola, 

 P. de B., T. ustus, Walk., T. fraternus, Macq., T. atrimanus, Lw., 

 T. variabilis, Lw., T. insignis, Lw., T. laverani, Sure, T. nagamiensis. 

 Cart., T. gratus, Lw., T. obscuripes, Ric, T. medionotatus, Aust., 

 and T. pertinens, Aust. The sites of some Tabanid breeding places 

 are illustrated by photographs 



